Field of the Invention
The invention pertains to the field of horseshoes. More particularly, the invention pertains to a cushioned horseshoe.
Description of Related Art
Cushioned horseshoes are used to aid in absorbing the impact of the hoof with the ground. Some cushioned horseshoes have an upper and a lower metal shoe, with a resilient cushion between. The upper and lower shoes are often held together by screws or rivets, with the cushion between. Other cushioned horseshoes only have a lower metal shoe with a rubber pad of at least 90 durometer.
In most of the prior art cushioned horseshoe designs, the nails which hold the shoe against the horse's hoof are driven into holes in the lower (ground-contacting) shoe, so that the nails press against the ground-contacting surface of the shoe, as in a conventional non-cushioned horseshoe. Therefore, every time the animal takes a step the cushion is compressed between the upper and lower shoe. This causes the lower surface of the shoe to be released from the nail as the cushion is compressed, and then to contact the surface as the hoof is lifted and the cushion rebounds. This gradually works the nails out, causing loss of the shoe.
Where screws or rivets are used, the shoe will have the same working problem on the screws or rivets as on the nails in the nailed-through shoes when the cushion is compressed, and the heads of the screws or rivets which are on the ground-contacting surface of the shoe will also wear against the ground. These effects will cause the cushioned horseshoe to fall apart as the rivets or screws are lost. Also, dirt will build up under the screw or nail heads when the cushion is compressed, limiting the amount of rebound possible, and eventually eliminating the cushioning effect.
Some prior art cushioned horseshoes avoided the nail-working problem by putting a slot in the lower shoe, so that the nail passes through the lower shoe and presses against the upper shoe and, in some cases, the rubber cushion.
In two-piece cushioned horseshoes where the upper and lower shoes are held together by screws or rivets, it is not possible to cold-size the shoe in one piece. The upper and lower shoes must be sized separately, and after that it is very difficult to get the holes for the screws or rivets to line up again.
U.S. Pat. No. 2,103,718, issued in 1937 to Goodwin, is a cushioned horseshoe in which the rubber cushion is vulcanized against the upper and lower shoes. Goodwin's shoe uses vertical flanges (see FIGS. 2, 4 5 and 8) which protrude from the lower shoe along inside and outside edges of the upper shoe, which cause metal-to-metal contact between the upper and lower shoes. The shoe lacks interlocking internal flanges and recesses on the upper and lower shoes to limit relative movement.